When putting oil that close to the barrel Just make sure to fire it plenty of times without the barrel on so you don't coat the inside with oil. 1-2 drops in the ASA will do the trick just as well. If you are having leakage problems with that little oil it's probably a good time to replace your cupseal. Do you have any gauges on your marker? If that's the case I think it's better to add the oil after the gauge. (which may be what you're doing afterall!)